TY - JOUR
T1 - In vitro and in vivo insulinotropic properties of the multifunctional frog skin peptide hymenochirin-1B
T2 - A structure-activity study
AU - Owolabi, Bosede O.
AU - Ojo, Opeolu O.
AU - Srinivasan, Dinesh K.
AU - Conlon, J. Michael
AU - Flatt, Peter R.
AU - Abdel-Wahab, Yasser H.A.
N1 - Funding Information:
This study was supported by the University of Ulster Research Strategy Funding and an award of a University Vice Chancellor Research Studentship to DKS. We thank Professor D. Drucker for access to GLUTag cells.
Publisher Copyright:
© 2015 Springer-Verlag Wien.
PY - 2016/2/1
Y1 - 2016/2/1
N2 - Hymenochirin-1b (Hym-1B; IKLSPETKDNLKKVLKGAIKGAIAVAKMV.NH2) is a cationic, α-helical amphibian host-defense peptide with antimicrobial, anticancer, and immunomodulatory properties. This study investigates the abilities of the peptide and nine analogues containing substitutions of Pro5, Glu6, and Asp9 by either l-lysine or d-lysine to stimulate insulin release in vitro using BRIN-BD11 clonal β cells or isolated mouse islets and in vivo using mice fed a high-fat diet to produce obesity and insulin resistance. Hym-1B produced a significant and concentration-dependent increase in the rate of insulin release from BRIN-BD11 cells without cytotoxicity at concentrations up to 1 μM with a threshold concentration of 1 nM. The threshold concentrations for the analogues were: [P5K], [E6K], [D9K], [P5K, E6K] and [E6K, D9k] 0.003 nM, [E6K, D9K] and [D9k] 0.01 nM, [P5K, D9K] 0.1 nM and [E6k] 0.3 nM. All peptides displayed cytotoxicity at concentrations ≥1 μM except the [P5K] and [D9k] analogues which were non-toxic at 3 μM. The potency and maximum rate of insulin release from mouse islets produced by the [P5K] peptide were significantly greater than produced by Hym-1B. Neither Hym-1B nor the [P5K] analogue at 1 μM concentration had an effect on membrane depolarization or intracellular Ca2+. The [P5K] analogue (1 μM) produced a significant increase in cAMP concentration in BRIN-BD11 cells and stimulated GLP-1 secretion from GLUTag cells. Down-regulation of the protein kinase A pathway by overnight incubation with forskolin completely abolished the insulin-releasing effects of [P5K]hym-1B. Intraperitoneal administration of the [P5K] and [D9k] analogues (75 nmol/kg body weight) to high-fat-fed mice with insulin resistance significantly enhanced glucose tolerance with a concomitant increase in insulin secretion. We conclude that [P5K]hym-1B and [D9k]hym-1B show potential for development into anti-diabetic agents.
AB - Hymenochirin-1b (Hym-1B; IKLSPETKDNLKKVLKGAIKGAIAVAKMV.NH2) is a cationic, α-helical amphibian host-defense peptide with antimicrobial, anticancer, and immunomodulatory properties. This study investigates the abilities of the peptide and nine analogues containing substitutions of Pro5, Glu6, and Asp9 by either l-lysine or d-lysine to stimulate insulin release in vitro using BRIN-BD11 clonal β cells or isolated mouse islets and in vivo using mice fed a high-fat diet to produce obesity and insulin resistance. Hym-1B produced a significant and concentration-dependent increase in the rate of insulin release from BRIN-BD11 cells without cytotoxicity at concentrations up to 1 μM with a threshold concentration of 1 nM. The threshold concentrations for the analogues were: [P5K], [E6K], [D9K], [P5K, E6K] and [E6K, D9k] 0.003 nM, [E6K, D9K] and [D9k] 0.01 nM, [P5K, D9K] 0.1 nM and [E6k] 0.3 nM. All peptides displayed cytotoxicity at concentrations ≥1 μM except the [P5K] and [D9k] analogues which were non-toxic at 3 μM. The potency and maximum rate of insulin release from mouse islets produced by the [P5K] peptide were significantly greater than produced by Hym-1B. Neither Hym-1B nor the [P5K] analogue at 1 μM concentration had an effect on membrane depolarization or intracellular Ca2+. The [P5K] analogue (1 μM) produced a significant increase in cAMP concentration in BRIN-BD11 cells and stimulated GLP-1 secretion from GLUTag cells. Down-regulation of the protein kinase A pathway by overnight incubation with forskolin completely abolished the insulin-releasing effects of [P5K]hym-1B. Intraperitoneal administration of the [P5K] and [D9k] analogues (75 nmol/kg body weight) to high-fat-fed mice with insulin resistance significantly enhanced glucose tolerance with a concomitant increase in insulin secretion. We conclude that [P5K]hym-1B and [D9k]hym-1B show potential for development into anti-diabetic agents.
KW - Amphibian skin peptide
KW - Hymenochirin-1b
KW - Insulin release
KW - Type 2 diabetes
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UR - http://www.scopus.com/inward/citedby.url?scp=84958754158&partnerID=8YFLogxK
U2 - 10.1007/s00726-015-2107-x
DO - 10.1007/s00726-015-2107-x
M3 - Article
C2 - 26439377
AN - SCOPUS:84958754158
SN - 0939-4451
VL - 48
SP - 535
EP - 547
JO - Amino Acids
JF - Amino Acids
IS - 2
ER -